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Classification of Living Things A Little History The Earth is 4.6 billion years old and microbial life is thought to have first appeared between 3.8 and 3.9 billion years ago. In fact, 80% of Earth's history was exclusively microbial life. Microbial life is still the dominant life form on Earth. The National Science Foundation’s “Tree of Life” project estimates that there could be anywhere from 5 million to 100 million species on the planet, but science has only identified about 2 million. “We’ve only touched the surface of understanding animal life,” said entomologist Brian Fisher of the California Academy of Sciences. “We’ve discovered just 10 percent of all living things on this planet.” Why do we classify things? Supermarket aisles Libraries Classes Teams/sports Members of a family Roads Cities Money What is classification? Classification: putting things into orderly groups based on similar characteristics Taxonomy: the science of describing, naming, and classifying organisms Early classification Aristotle grouped everything into simple groups such as animals or plants He then grouped animals according to if they had blood or didn’t have blood, and if they had live young or laid eggs, and so on… Binomial Nomenclature Developed by Carolus Linnaeus Swedish Biologist 1700’s Two-name system Genus and species named using Latin or Greek words When Linnaeus developed his system of classification, there were only two kingdoms, Plants and Animals. However, the use of the microscope led to the discovery of new organisms and the identification of differences in cells. A two-kingdom system was no longer useful. Today the system of classification includes six kingdoms. The Six Kingdoms: Plants, Animals, Protists, Fungi, Archaebacteria, & Eubacteria. How are organism placed into their kingdoms? · Cell type, complex or simple · Their ability to make food · The number of cells in their body Archaebacteria In 1983, scientists took samples from a spot deep in the Pacific Ocean where hot gases and molten rock boiled into the ocean from the Earth’s interior. To their surprise they discovered unicellular (one cell) organisms in the samples. These organisms are today classified in the kingdom, Archaebacteria. Archaebacteria are found in extreme environments such as hot boiling waterand thermal vents under conditions with no oxygen or highly acid environments. Finding Archaebacteria: The hot springs of Yellowstone National Park, USA, were among the first places Archaebacteria were discovered. The biologists pictured above are immersing microscope slides in the boiling pool onto which some archaebacteria might be captured for study. Eubacteria Like archaebacteria, eubacteria are complex and single celled. Most bacteria are in theEUBACTERIA kingdom. They are the kinds found everywhere and are the ones people are most familiar with. Eubacteria are classified in their own kingdom because their chemical makeup is different. Most eubacteria are helpful. Some produce vitamins and foods like yogurt. However, these eubacteria, Streptococci pictured above, can give you strep throat! One celled No separate nucleus Example: bacteria Protist Protists Slime molds and algae are protists. Sometimes they are called the odds and ends kingdom because its members are so different from one another. Protists include all microscopic organisms that are not bacteria, notanimals, not plants and not fungi. Most protists are unicellular. You may be wondering why those protists are not classified in the Archaebacteria or Eubacteria kingdoms. It is because, unlike bacteria, protists are complex cells. These delicate looking diatoms are classified in the protist kingdom. Most one celled Have nucleus and other cell structures Examples: algae, amoeba Fungus Fungi Mushrooms, mold and mildew are all examples of organisms in the kingdom fungi. Most fungi are multicellular and consists of many complex cells. Fun Facts about Fungi Some fungi taste great and others can kill you! Fungi are organisms that biologists once confused with plants, however, unlike plants, fungi cannot make their own food. Most obtain their food from parts of plants that are decaying in the soil. Many celled Cannot move Absorb nutrients from other organisms Examples: mushrooms, yeast, molds Plant You are probably quite familiar with the members of this kingdom as it contains all the plants that you have come to know flowering plants,mosses, and ferns. Plants are all multicellular and consist of complex cells. With over 250,000 species, the plant kingdom is the second largest kingdom. Plant species range from the tiny green mosses to giant trees. In addition plants are autotrophs,organisms that make their own food. Many-celled Cannot move Autotrophs (Use energy from the sun to make sugars) Animal Animals The animal kingdom is the largest kingdom with over 1 million known species. Sumatran Tiger - Kingdom: Animalia, Phylum, Chordata, Class Mammalia, Order Carnivora, Family Felidae, Genus Pathera, Species tigris All animals consist of many complex cells. They are also heterotrophs. Members of the animal kingdom are found in the most diverse environments in the world. Many-celled Most can move Get energy by consuming other organisms Examples: invertebrates, fish, birds, mammals The modern system of classification has 8 levels: Domain Order Kingdom Family Phylum Genus Class Species Helpful way to remember the 8 levels Dumb kids playing catch on freeways get squashed Or…make up your own… DKPCOFGS Using the Classification System Field guides help identify organisms. -they highlight differences between similar organisms (like trees) Taxonomic Key (Dichotomous Key) -paired statements that describe the physical characteristics of different organisms Rules used to write scientific names Homo sapiens An organism’s genus is always written first; the organism’s species is always written second The genus is Capitalized; the species is written in lower case Scientific names of organisms are always italicized or underlined Modern Taxonomy The Evidence used to classify into taxon groups 1) Embryology (splits animal kingdom) 2) Chromosomes / DNA 3) Biochemistry 4) Physiology (structure/function) 5) Evolution 6) Behavior Taxonomic Key 1a Fruits occur singly ................................................. Go to 3 1b Fruits occur in clusters of two or more ................ Go to 2 2a Fruits are round ................................................... Grapes 2b Fruits are elongate ............................................... Bananas 3a Thick skin that separates easily from flesh .........Oranges 3b Thin skin that adheres to flesh .............................. Go to 4 4a More than one seed per fruit ............................ Apples 4b One seed per fruit ............................................ Go to 5 5a Skin covered with fuzz.................... Peaches 5b Skin smooth, without fuzz........................... Plums What steps would you use to identify an apple?
